Airplane engines require parts that are wear resistant, thermally stable and light in weight. Many airplane engines make use of an axial compressor to compress the incoming air before the air is passed to the combustor section of the engine. The axial compressor uses alternating rows of rapidly rotating blades, i.e., rotors, and rows of stator vanes that are fixed and do not rotate. The combined action of the rotor blades and the stator vanes increases the air pressure. The stator vanes can be variable, i.e., they may turn or pivot on their longitudinal axis, to allow better control of airflow and pressure. A row of rotors and a row of stators is referred to as a stage. An axial compressor typically has several stages. The stator vanes are held radially between the outer engine casing and an inner shroud. An inner shroud is fixed in place about the rotating shaft of the engine. The vane end, referred to as a spindle or trunnion, fits in a recess machined into the inner shroud. When the shroud and the vanes are both composed of metal, wear can occur between the vane spindle and the inner shroud. Polymer bushings of a high temperature resistant, wear resistant polymer such as Vespel® brand polyimide (available from DuPont Co., Wilmington, Del.) can be used to reduce metal-to-metal wear.
There is a need for airplane engine parts that are lighter than metal, thermally stable and wear resistant.